I have wondered this same thing. Sometimes they say the prize will be awarded in the form of a check which "may" be used to purchase... But sometimes, as in your example, they seem pretty specific. It's hard to believe a washer and dryer would cost $5,000 -- Might pay that much though if they folded, ironed and hung the clothes too. :-)
I wrote to DIY once when they were having a $100,000 garage makeover sweepstake and asked them if I won, would the money have to be spent on my garage. They said no, I could use it anyway I chose. I wanted to make sure before I took the time to enter, as there is no way I would want to spend $100,000 on my garage.
I too will be interested in how other sweepers intrepret these rules or experiences they have had with similar sweeps.